Administering an injection is a process which presents a number of risks and challenges for users and healthcare professionals, both mental and physical. Injection devices typically fall into two categories—manual devices and autoinjectors. In a conventional manual device, manual force is required to drive a medicament through a needle. This is typically done by some form of button/plunger that has to be continuously pressed during the injection. There are numerous disadvantages associated with this approach. For example, if the button/plunger is released prematurely, the injection will stop and may not deliver an intended dose. Further, the force required to push the button/plunger may be too high (e.g., if the user is elderly or a child). And, aligning the injection device, administering the injection and keeping the injection device still during the injection may require dexterity which some patients (e.g., elderly patients, children, arthritic patients, etc.) may not have.
Autoinjector devices aim to make self-injection easier for patients. A conventional autoinjector may provide the force for administering the injection by a spring, and trigger button or other mechanism may be used to activate the injection. Autoinjectors may be single-use or reusable devices.
Autoinjectors may be mechanical, electro-mechanical or fully electronic. Conventional mechanical autoinjectors may automatically provide the required force for needle insertion and medicament delivery, but may not provide additional functionality (e.g., alignment verification, injection site verification, etc.) which may be capable with electro-mechanical and fully electronic autoinjectors.
WO 2005/077441 A2 discloses a hand-held, electronically controlled injection device for injecting preset doses of liquid medications, having a housing for receiving a cartridge containing the liquid medication and having a contact surface for contacting a patient's skin; and actuator means for moving the cartridge within the housing to and from the contact surface.
U.S. Pat. No. 3,712,301 A discloses a hypodermic injector comprising a sleeve housing a cocked spring impelled plunger, a cartridge holder with a cannula pierceable stopper at the front end thereof attached to the sleeve and a cartridge with front end attached cannula in the holder wherein the rear end only of the cartridge is frictionally retained in the holder and in air tight sealing engagement therewith, the cartridge being otherwise substantially unrestrained from movement with respect to the holder, the free end of the cannula lying within the holder until the plunger is released, all to maintain cannula sterility and yet allow rapid movement of the cartridge in the holder when the plunger is operative.
U.S. Pat. No. 3,742,948 A discloses a hypodermic syringe comprising a liquid container and a needle connected thereto at one end, which assembly is incorporated in a housing, the liquid container being bounded at the other end by a piston, and an operating mechanism being present to exert a force on the piston, one or more blocking elements being present for locking the operating mechanism or the piston against movement relative to the liquid container, the housing showing a diameter transition such that when the blocking elements pass along it, they are moved radially so that the blocking is removed and the piston penetrates into the liquid container so that the liquid flows out through the needle.
EP 2 468 340 A1 discloses an auto-injector for administering a dose of a liquid medicament, comprising:—a substantially tubular front-end device adapted to contain a syringe with an injection needle and a barrel containing the dose of the medicament and comprising a needle shroud adapted to rest on the skin of a patient receiving an injection and—a reusable backend device comprising—a housing, a plunger connected to or adapted to engage a stopper providing a fluid tight seal for a distal end of the barrel,—a motor for displacing the plunger connected to the stopper, wherein the front-end device is attachable to the backend device, wherein the needle shroud is slidably arranged with respect to the injection needle and wherein an interlock switch is capable of detecting an axial position of the needle shroud.
Thus, there remains a need for an improved autoinjector.